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arXiv:2407.03943 · Physical Review A

Non-Markovian-environment-induced anomaly in steady-state quantum coherence

Arapat Ablimit, Zhao-Ming Wang, Feng-Hua Ren, Paul W. Brumer, Lian-Ao Wu

Published Nov 21, 2024• 6 citations
arXivHTMLPDF

Abstract

Environment-induced steady-state quantum coherence (SSQC) is a captivating phenomenon that challenges conventional understandings of decoherence. In this article, we delve into the foundational aspects of environment-induced SSQC, shedding light on its emergence within the framework of system-bath interactions. Starting from a microscopic system-bath-coupled model, we investigate the dependence of SSQC on environmental memory effects, the bath temperature, the system-bath coupling strength, and squeezing parameters. Our findings reveal that the environment not only acts as a generator but also as a disruptor of SSQC. A peak will exist for a non-Markovian bath, which is a result of competition between these two mechanisms. Interestingly, the peak disappears in the Markovian case. Additionally, we observe that the generated SSQC can be further amplified through environment squeezing.

DOI
10.1103/physreva.110.052220

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Environment-induced steady-state quantum coherence (SSQC) is a captivating phenomenon that challenges conventional understandings of decoherence. In this article, we delve into the foundational aspects of environment-induced SSQC, shedding light on its emergence within the framework of system-bath interactions. Starting from a microscopic system-bath-coupled model, we investigate the dependence of SSQC on environmental memory effects, the bath temperature, the system-bath coupling strength, and squeezing parameters. Our findings reveal that the environment not only acts as a generator but also as a disruptor of SSQC. A peak will exist for a non-Markovian bath, which is a result of competition between these two mechanisms. Interestingly, the peak disappears in the Markovian case. Additionally, we observe that the generated SSQC can be further amplified through environment squeezing.
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Steady-state coherence in open quantum systems is crucial for quantum technologies, yet its behavior is not fully understood due to the interplay between collective and individual decoherence. While collective decoherence is thought to induce steady-state coherence, experiments often fail to observe this because of individual decoherence. We study a system of two harmonic oscillators coupled to both individual and collective environments, introducing a tunable parameter to adjust the decoherence proportions. By analytically solving the exact dynamical equations, we find that steady-state coherence depends on the initial state under collective decoherence, but not under partial decoherence. Interestingly, non-Markovianity induces rich and complex steady-state coherence behaviors. Our results clarify the role of non-Markovian decoherence in quantum systems and provide a benchmark for assessing approximate methods for modeling quantum processes.
The Liouvillian skin effect and the non-Hermitian skin effect have both been used to explain the localization of eigenmodes near system boundaries, though the former is arguably more accurate in some regimes due to its incorporation of quantum jumps. However, these frameworks predominantly focus on weak Markovian interactions, neglecting the potentially crucial role of memory effects. To address this, we investigate, utilizing the powerful hierarchical equations of motion method, how a non-Markovian environment can modify the Liouvillian skin effect. We demonstrate that a non-Markovian environment can induce a “thick skin effect,” where the skin mode broadens and shifts into the bulk. We further identify that the skin-mode quantum coherence can only be generated when the coupling contains counter-rotating terms, leading to the coherence delocalization and oscillatory relaxation with a characteristic linear scaling with system size. Remarkably, both the skin-mode and steady-state coherence exhibit resistance to decoherence from additional environmental noise. These findings highlight the profound impact of system-bath correlations on relaxation and localization, revealing unique phenomena beyond conventional Markovian approximations.
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In this manuscript, we study the Schrödinger cat state transfer in a quantum optical version of Newton's cradle in non-Markovian environment. Based on a non-Markovian master equation, we show that the cat state can be transferred purely through the memory effect of the non-Markovian common environment, even without any direct couplings between neighbor cavities. The mechanism of the environment induced cat state transfer is analyzed both analytically and numerically to demonstrate that the transfer is a unique phenomenon in non-Markovian regime. From this example, the non-Markovian environment is shown to be qualitatively different from the Markovian environment reflected by the finite versus zero residue coherence. Besides, we also show the influence of environmental parameters are crucial for the transfer. We hope the cat state transfer studied in this work may shed more light on the fundamental difference between non-Markovian and Markovian environments.